RE: auto vs. over and under
I've shot a Browning Auto 5 in 20 gauge for over 25 years and have killed everything from doves to deer with it, though it's gotten precious little action in the last few years.
I recently bought a Ruger Red Label o/u in 20 gauge for dove and quail hunting. While I've not fired the weapon yet, it sure feels good when shouldered.
I'm hoping I like it as much in the field as I do at the house.
El Gringo